1. Field of the Invention
This invention relates to photographic cameras, and more particularly to an automatic exposure control apparatus having a digital computer to which various exposure control parameters are applied after being digitized.
2. Description of Prior Art
It is known to provide an automatic exposure control apparatus for controlling either the exposure time or the exposure aperture size of a camera in such a manner that various exposure control parameters are converted to digital signals which are then applied to a digital computer cooperating with the shutter and diaphragm mechanisms of the camera. It is also known, for example, in controlling the aperture size of the lens aperture mechanism in accordance with the output pulse of the digital computer as derived in conformance with the preselected exposure control parameters such as shutter speed, film sensitivity and object brightness level, to convert ever varying actual aperture sizes of the lens aperture mechanism to corresponding resistance values of a variable resistor, then upon application of a voltage on the resistor to convert the resistance values to analog electrical signals, then to convert the analog signals to digital signals by use of an analog-to-digital converter, and finally upon attainment of the digital signals to a level dependent upon the output of the computer to arrest the lens aperture mechanism, whereby the resultant exposure aperture size is adjusted in conformance with the output of the computer. Such an exposure control has drawbacks in that the necessity of the analog-to-digital converter increases the complexity of the electrical circuitry of the exposure control apparatus which in turn causes an increase in the bulk of the apparatus itself. These drawbacks become serious when designing compact, low-cost cameras with exposure control apparatus of the character described.